Published data for this review were identified by a searching Medline with the term “dyspnea”. Subsets of the original search were also done with the additional keywords “pathophysiology” and “therapy” and publication type “clinical trial”. Further papers were identified from the personal collections of the authors and from the bibliographies of papers identified by the above searches. Only papers published in English after 1966 were used.
ReviewClinical management of dyspnoea
Section snippets
Pathophysiology of dyspnoea
The pathophysiology of dyspnoea is incompletely understood. Most data come from studies of healthy volunteers with experimentally induced dyspnoea or from patients with COPD. Dudgeon and Lertzman undertook a prospective analysis of 100 patients with dyspnoea and advanced cancer in an attempt to elucidate the causes.4 They found that 49% had lung cancer; 65% had lung or pleural involvement; 40% were hypoxaemic with oxygen saturation of less than 90%; 12% had arterial carbon dioxide partial
Diagnosis
The gold standard for diagnosis of dyspnoea is the patient's self-report. There is no other reliable, objective measure of the disorder. Measurements of respiratory rate, oxygen saturation, and arterial blood gases are not correlated with and do not measure dyspnoea. For example, patients may be hypoxaemic but not dyspnoeic, or dyspnoeic but not hypoxaemic.
In the clinical research setting, dyspnoea can be measured in several ways. Functional assessment tools such as the shuttle walking test14
Symptomatic management
The therapeutic goal of symptomatic management of dyspnoea is to relieve the patient's sense of the effort of breathing. This aim can be achieved by pursuing one or more strategies, including both pharmacological and non-pharmacological interventions. The strategies need not be limited to patients for whom efforts to relieve the underlying causes are thought to be futile or excessively onerous.
Opioids
Opioids are the first line of therapy for symptomatic control of dyspnoea. Opioids decrease exercise-induced dyspnoea and increase exercise tolerance in patients with COPD.18, 19 Bruera and colleagues were the first to carry out a study in cancer patients.20 In their placebo-controlled crossover study, opioids relieved dyspnoea without evidence of respiratory depression. There was no change in respiratory rate or oxygen saturation. Mazzocato and co-workers showed that in opioid-naïve patients,
Anxiolytics
The role of anxiety in dyspnoea remains unclear. Many patients report anxiety concurrent with the feeling of breathlessness. Dyspnoea can lead to anxiety, and anxiety can exacerbate dyspnoea. Opioids alone may break the cycle by relieving dyspnoea. Although the opioids may initially have anxiolytic properties, patients typically become tolerant to these effects. Therefore, anxiolytic properties alone are unlikely to explain the effect of opioids on dyspnoea.
Anxiolytics (such as benzodiazepines)
Oxygen
Oxygen can reverse hypoxaemia. If this feature is the cause of dyspnoea, oxygen may be the only therapy required. However, the perceived benefit in patients with cancer who are dyspnoeic far exceeds the number who have hypoxaemia.
There have been only a few small studies assessing oxygen therapy for hypoxaemia in patients with cancer. One randomised, double-blind cross-over study showed that oxygen improved dyspnoea in these patients,35 but another controlled study showed no advantage of oxygen
Cognitive/behavioural interventions
Dyspnoea also has cognitive and emotional components. Bredin and colleagues assessed the effect of a nurse-run dyspnoea clinic in a multicentre, randomised, controlled study.40 The concept is similar to pulmonary rehabilitation clinics for COPD. The intervention group were taught breathing control, activity pacing, and relaxation techniques, and were given psychosocial support. Compared with controls, the patients who underwent the intervention showed improvement in dyspnoea scores, performance
Management of underlying causes
Both the degree of diagnostic investigation and the choice of interventions must be guided by the patient's goals and the extent of disease. The patient's functional status and prognosis are important factors to consider. After risk/benefit analysis, treatment should be directed at reversible causes when possible, without neglecting concurrent symptomatic treatment.
Dyspnoea directly related to the cancer can potentially be treated with resection, chemotherapy, or radiotherapy. Obstruction can
Terminal care
As patients approach the last hours or days of life, there may be changes in breathing patterns that relatives interpret as dyspnoea. Rapid shallow breathing, periods of apnoea, and a Cheyne-Stokes respiratory pattern are common end-of-life breathing patterns.44 A few last reflex breaths may signal death. Family carers should be educated that the comatose patient does not experience these breathing patterns as dyspnoea. In some cases, to alleviate the suffering of family carers, low-dose
Refractory dyspnoea
There may be a few patients for whom the symptomatic approaches outlined in this review do not relieve dyspnoea. In these rare cases, sedation can be given ethically for the patient to be relieved of the awareness of the symptom.45 After informed consent has been obtained, medications such as benzodiazepines, neuroleptics, barbiturates, or propofol may be titrated to induce sedation. Opioids alone are unreliable sedatives. Doses should be titrated to provide the desired degree of sedation. If
Conclusions
Dyspnoea is a significant clinical problem for cancer patients. Effective clinical management strategies will relieve the symptom to the satisfaction of the majority of patients. Opioids are the first-line therapy for control of dyspnoea. Oxygen and benzodiazepines may be useful adjuncts. Symptomatic management of dyspnoea can be pursued concurrently with treatment directed at removing underlying causes. For refractory cases, sedation may be appropriate and ethical under the principle of double
Search strategy and selection criteria
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